Maciej W. Rozycki wrote:
On Wed, 4 Aug 2004, Nigel Stephens wrote:
Here are my proposals I've referred to previously. Instruction countsIMHO handling a shift by zero correctly is important.
are 9, 9 and 10, respectively, as I've missed an additional instruction
required to handle shifts by 0 (or actually any multiples of 64).
Agreed, hence an additional instruction needed.
"not %1, %3\n\t" "srlv %1, %L2, %1\n\t" "srl %1, %1, 1\n\t"
Why not the shorter:
"neg %1, %3\n\t"
"srlv %1, %L2, %1\n\t"
Notice the difference -- this shorter code doesn't handle shifts by zero
correctly. ;-)
Ah yes, I see. I did it with a conditional move to fix up after the shift, but same result.
And then in __ashrdi3:
"andi %1, %3, 0x20\n\t" ".set push\n\t" ".set noat\n\t" "sra $1, %M2, 31\n\t" "movn %L0, %M0, %1\n\t" "movn %M0, $1, %1\n\t" ".set pop"
Cute, but I think that should be
"sra $1, %M0, 31\n\t"
(i.e %M0 not %M2)
Well, I've tested it for all shift counts and it works properly as is -- we care of the value of bit #31 to be shifted only and at this stage it's the same in both registers. So it's just a matter of style.
OK, I see
Nigel
